Allow querying all attributes on a file

Add a function, git_all_attrs(), that reports on all attributes that
are set on a path.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

attr.c

@@ -747,6 +747,34 @@ int git_checkattr(const char *path, int num, struct git_attr_check *check)
 	return 0;
 }
 
+int git_all_attrs(const char *path, int *num, struct git_attr_check **check)
+{
+	int i, count, j;
+
+	collect_all_attrs(path);
+
+	/* Count the number of attributes that are set. */
+	count = 0;
+	for (i = 0; i < attr_nr; i++) {
+		const char *value = check_all_attr[i].value;
+		if (value != ATTR__UNSET && value != ATTR__UNKNOWN)
+			++count;
+	}
+	*num = count;
+	*check = xmalloc(sizeof(**check) * count);
+	j = 0;
+	for (i = 0; i < attr_nr; i++) {
+		const char *value = check_all_attr[i].value;
+		if (value != ATTR__UNSET && value != ATTR__UNKNOWN) {
+			(*check)[j].attr = check_all_attr[i].attr;
+			(*check)[j].value = value;
+			++j;
+		}
+	}
+
+	return 0;
+}
+
 void git_attr_set_direction(enum git_attr_direction new, struct index_state *istate)
 {
 	enum git_attr_direction old = direction;